Advertisements
Advertisements
Question
Show, using a simple polaroid, that light waves are transverse in nature. Intensity of light coming out of a polaroid does not change irrespective of the orientation of the pass axis of the polaroid. Explain why.
Solution
To show light waves are transverse in nature:
Take two polaroids T1 and T2 cut with their faces parallel to the axis of the crystal
When polaroid T1 is rotated about the direction of the propagation of light as axis, the intensity of the transmitted light remains the same. When T2 is rotated gradually, the intensity goes on decreasing and the transmitted light disappears completely when T2 is perpendicular to T1.
This happens because the polaroid allows only those vibrations of light which are parallel to its axis. This is true only if light has vibrations in all possible directions and hence is a transverse wave.
Light waves are transverse waves. So, they have electric vectors in all possible directions. When a polaroid is placed in between the path of the light, the electric vectors which are parallel to the pass-axis of the polaroid pass through it. Even if the polaroid is rotated, there would be other electric vectors which pass through it. So, the intensity of light does not change irrespective of the orientation of pass-axis of the polaroid.
APPEARS IN
RELATED QUESTIONS
Draw a neat labelled diagram showing the plane of vibration and plane of polarisation for polarised light.
Find an expression for intensity of transmitted light when a polaroid sheet is rotated between two crossed polaroids. In which position of the polaroid sheet will the transmitted intensity be maximum?
What is the Brewster angle for air to glass transition? (Refractive index of glass = 1.5)
What does a polaroid consist of? How does it produce a linearly polarised light?
Which of the following properties shows that light is a transverse wave?
State Brewster’s law.
Polarisation of light is the only phenomenon that establishes ______.
Consider a light beam incident from air to a glass slab at Brewster’s angle as shown in figure. A polaroid is placed in the path of the emergent ray at point P and rotated about an axis passing through the centre and perpendicular to the plane of the polaroid.
Figure shown a two slit arrangement with a source which emits unpolarised light. P is a polariser with axis whose direction is not given. If I0 is the intensity of the principal maxima when no polariser is present, calculate in the present case, the intensity of the principal maxima as well as of the first minima.
A polarizer - analyser set is adjusted such that the intensity of light coming out of the analyser is just 10% of the original intensity. Assuming that the polarizer - analyser set does not absorb any light, the angle by which the analyser need to be rotated further to reduce the output intensity to be zero, is ______.
